Many polymers are known to be useful, in dissolved form, for reducing the flowing friction of various liquids, e.g., hydrocarbons in pipelines. Generally, the friction reduction capabilities of such polymers are directly proportional to molecular chain length. Reduction of chain length commonly occurs through exposure of the dissolved polymer to the action of pumps, etc. In a long pipeline it is therefore desirable to provide freshly dissolved polymer all along the length of the pipeline. To accomplish this, the polymer is injected in the line as solid particles, in a range of size, and allowed to dissolve in situ in the flowing hydrocarbon in the pipeline. Smaller particles more quickly dissolve and provide friction reduction in the first segments of the pipeline, and the larger particles pass through pumps without adverse effect and provide friction reduction in subsequent segments of the pipeline. However, use of such polymer particles is not without problems. For example, the particles are easily compressed into large chunks. Storage for a short period of time will cause the polymer to cold flow together under its own weight when piled to heights in excess of a few feet. To break up the lumps of compressed polymer requires expensive equipment and considerable time. The cold flow effect causing lumping, also makes the polymer unsuitable for direct injection with a suspending medium to carry the polymer particles.
Storage of the polymer in a suspending medium facilitates injection and alleviates cold flow problems but in turn leads to other equally difficult problems. In a water suspension, the polymer tends to float and easily fouls pumping equipment. In an oil suspension, the polymer will begin to dissolve and form an oily, spongy mass after a few hours time which can only be handled with great difficulty.
The present invention overcomes the above and other problems by providing a new technique for storing and injecting solid polymer particles into pipelines.
Patents pertinent to the present disclosure include U.S. Pat. Nos. 3,884,252; 2,306,926; 2,486,650; 2,648,572; 3,720,216; 3,730,275 and 3,736,288.